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Mineralogical Evolution and Expansion of Cement Pastes in a Sulfate-Confined Environment.

Authors :
Pouya, Julie
Neji, Mejdi
De Windt, Laurent
Péralès, Frédéric
Socié, Adrien
Corvisier, Jérôme
Source :
Minerals (2075-163X); Jan2023, Vol. 13 Issue 1, p1, 19p
Publication Year :
2023

Abstract

The geologic disposal of radioactive waste could lead to confined conditions in which cementitious materials impose a moderate alkaline pH, in which the rocks supply sulfate ions at rather low concentrations. In this context, the purpose of this work was to study the degradation of cement pastes under such conditions using a non-renewed 30 mmol/L Na<subscript>2</subscript>SO<subscript>4</subscript> solution without pH regulation. Samples were investigated through laboratory testing and numerical modeling. XRD, SEM–EDS, and micro-indentation acquisitions were performed to follow the evolution of chemical, mineralogical, and mechanical properties during the weak external sulfate attack. Reactive transport modeling was performed with the HYTEC code. Based on these results, the Young's moduli of the degraded zones were estimated using analytical homogenization. Decalcification occurred despite the high pH value of the solution and significantly affected the mechanical properties. Macroscopic swelling and cracking were caused by the formation of expansive sulfate minerals after 60 days, despite the low sulfate content of the tank solution. The modeling supported the discussion on the evolution of the mineral fronts (ettringite, portlandite, and gypsum). [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
2075163X
Volume :
13
Issue :
1
Database :
Complementary Index
Journal :
Minerals (2075-163X)
Publication Type :
Academic Journal
Accession number :
161560893
Full Text :
https://doi.org/10.3390/min13010001